Hydrogenation Of Aromatic Nitro Compounds Research Articles

Highly active CeO2-CuCo nanoparticles supported on hollow N-doped carbon spheres for boosting ammonia borane hydrolysis and tandem 4-nitrophenol reduction reactions

It’s a safe method to use high hydrogen density ammonia borane (AB) to facilitate the tandem hydrogenation of aromatic nitro compounds. While a major problem for tandem hydrogenation, the development of non-noble metal catalysts with high activity and stability is encouraging. This work involved the synthesis of highly active CeO2/CuCo nanoparticles support on hollow N-doped carbon spheres and its investigation for AB hydrolysis, taking into account the impacts of the HNCSs and CeO2 supports. Because CuCo alloy, CeO2, and HNCSs supports worked in concert, HNCSs@CeO2/CuCo was found to be the best catalyst. The activation energy achieved was comparable to the reported Pd- and Pt-based catalysts, with a value as low as 21.8 kJ/mol. Using AB as the in-situ H2 source, HNCSs@CeO2/CuCo exhibited a significant degree of activity in the one-pot tandem reduction of 4-NP with the turnover frequency of 2830.2 h−1, even surpassing over ten times of some noble metal catalysts. Following five consecutive cycles of reaction condition tuning, the HNCSs@CeO2/CuCo catalyst demonstrated a constant conversion efficiency. Also, the catalyst's uses for one-pot tandem reduction of other highly active aromatic nitro compounds were expanded.

Low-cost and highly stable Ni@NC materials synthesized from metal-organic framework precursors for selectively catalytic hydrogenation of p-nitrophenol under mild conditions

The catalytic hydrogenation of aromatic nitro compounds under mild conditions to generate amino compounds is a great challenge in terms of conversion, selectivity and stability. In this paper, two classes of nitrogen-doped carbon coated nickel nanoparticles, coined Ni@NC-P and displaced Ni@NC-T were prepared by high-temperature pyrolysis of MOFs using inexpensive terephthalic acid and high-priced trimesic acid as carbon source, respectively. One from the former class, namely the Ni@NC-P-500 catalyst, exhibits the best catalytic performance, which is superior to Ni@NC-T-500 Samples. For the selective hydrogenation of p-nitrophenol under mild conditions (60 °C, 2 h), the Ni@NC-P-500 catalyst shows >99.9 % conversion of p-nitrophenol and >99.9 % selectivity for p-aminophenol and can be recycled five times without obvious decrease of conversion and selectivity, thanks to its larger specific surface area (382.02 m2·g−1), smaller nickel particle size (8.2 nm), higher nitrogen content (especially pyridine nitrogen), higher electron-rich nickel content and less hydrophilic properties than that of the Ni@NC-T-500. The excellent stability and recyclability of the catalysts are mainly attributed to their core–shell structure, i.e., zero-valent nickel nanoparticles encapsulated within a nitrogen-doped carbon layer with an appropriate microporous structure, whereas zero-valent nickel nanoparticles have the ability to activate dihydrogen and block dioxygen.

Seafood waste derived Pt/Chitin nanocatalyst for efficient hydrogenation of nitroaromatic compounds

The fabrication of reliable, reusable and efficient catalyst is crucial for the conversion of nitroaromatic compounds into more chemically valuable amine-based molecules. In this study, a series of chitin supported platinum (Pt) catalysts with high catalytic activity, stability, and reusability were developed by using chitin derived from seafood waste as raw materials. The catalytic performance differences among these catalysts activated by different methods were investigated by hydrogenation of nitroaromatic compounds. The results showed that the multilayer hierarchical pore structure and abundance of hydroxyl and acetamido groups in chitin provided ample anchoring sites for Pt nanoparticles (NPs), ensuring the high dispersion of Pt NPs. Moreover, the interconnected channels between chitin nanofibrous microspheres facilitated rapid transport of reaction substrates. The best Pt/Chitin catalyst exhibited excellent catalytic activity and broad substrate applicability in hydrogenation of nitroaromatic compounds. Significantly, even after 20 runs, no discernible deactivation of activity was observed, demonstrating exceptional catalytic reusability. The application of seafood waste-based catalysts is conducive to the development of a green/sustainable society.

Palladium-Containing Aminated Activated Carbons: Hydrogenation of Aromatic Nitro Compounds

Palladium-Containing Aminated Activated Carbons: Hydrogenation of Aromatic Nitro Compounds

Interfacial nanoarchitectonics of nickel phosphide supported on activated carbon for transfer hydrogenation of nitroarenes under mild conditions

Metal phosphides are promising catalysts for hydrogenation reactions due to their unique ability to generate active hydrogen species which are essential for desired reactions. In this work, the hydrogenation potential of nickel phosphide (Ni2P) is explored for the transfer hydrogenation of aromatic nitro compounds using hydrazine hydrate as hydrogen source. The Ni2P was supported on activated carbon (AC) to facilitate highly exposed active reaction sites. The as-synthesized Ni2P-AC catalyst showed excellent catalytic potential for the hydrogenation of nitro compounds to corresponding amines with 100% conversion efficiency and resulted in excellent yields. The reaction conditions were optimized by varying different reaction parameters, such as time, temperature, solvents, catalyst amount and hydrogen sources. The developed reaction protocol is highly selective for nitro compounds having reduction susceptible functional groups like -Cl, -Br, –CHO, etc. The structure–activity relationship of the Ni2P-AC was also examined which suggested that both acidic and basic sites present in Ni2P-AC catalyst plays crucial role in hydrogenation reaction. Besides, an in-depth insight into the reaction mechanism illustrates that the reaction proceeds via N-phenyl hydroxylamine as the reaction intermediate. In addition, decent recyclability and stability of Ni2P-AC catalyst demonstrates its highly versatile nature for potential large-scale applications. The use of highly efficient Ni2P-AC catalyst for hydrogenation reactions can lead the way towards sustainable and effective industrial organic catalysis.

Co-oxide nanostructured catalysts tailored from layered double hydroxides for highly efficient hydrogenation of nitroarenes

Catalytic hydrogenation of aromatic nitro compounds containing multiple functional groups into corresponding amino compounds with high conversion rates, selectivity, and stability under mild conditions is a great challenge. Herein, we demonstrated low-cost CoAl LDH materials showing efficacy in the catalytic reduction of nitroarenes due to its highly active nature and own unique physical and chemical properties. The as-synthesized CoAl LDH catalysts exhibited a high conversion rate and selectivity for the hydrogenation of 7 different aromatic nitro compounds with different competing groups into the structure of the amino compounds using sodium borohydride under mild conditions (room temperature and 1 atm). The reaction was completed in a short time in between 5 and 150 min. The catalyst also showed excellent stability and could be reused over 8 times without considerably losing its activity.

Iron-Based Active Sites Encapsulated in Carbon Nanotubes for an Efficient Hydride Process

Selective and efficient catalytic hydrogenation of aromatic nitro compounds with multiple groups into target amines under mild conditions is highly desirable yet fairly challenging. Herein, we report a novel iron-based catalyst, which has metal nanoparticles (NPs) encapsulated in porous N-doped carbon nanotubes (NCT). The experimental and density functional theory results reveal that the NCT-supported porous structure provides the metal nanoparticles with more accessible active sites, leading to the Fe/Fe5C2@NCT-800 catalyst to show extremely high activity, chemoselectivity, and stability toward the hydrogenation of nitro compounds, affording full conversion within 0.2–0.3 h under room temperature.

NiOx-promoted Cu-based catalysts supported on AlSBA-15 for chemoselective hydrogenation of nitroarenes

Chemoselective hydrogenation of aromatic nitro compounds to the corresponding anilines is an environmentally benign technology for the production of key intermediates in manufacturing of pharmaceuticals, agrochemicals, dyes and fine chemicals. Non-noble metal Cu-based catalysts have been reported as a low-cost alternative but suffer from poor activity. Herein, by fabricating nickel oxide promoted Cu catalysts, a promoted activity was obtained in supported Cu-Ni bimetal catalyst system. Characterizations such as H2-TPR and XPS indicate a strong interaction between Cu and Ni, which contributes to its high activity and selectivity in hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN). Control experiments suggest that either monometallic copper or pure nickel oxide is less active for the reaction but the interaction of NiOx with Cu generates much more active species, resulting in significantly improved catalytic reactivity and selectivity. The activity was found to be highly dependent on the contents of Cu0 & Cu+ in Cu-Ni bimetal catalyst, as the specific reaction rates for hydrogenation of p-CNB grew linearly with the increment of Cu0 & Cu+ loadings. Kinetic studies and in-situ DRIFTS of p-CNB imply the 10Cu-5Ni/AlSBA-R catalyst possesses good capacity for the activation of hydrogen and nitro group, leading to high p-CNB conversion and p-CAN production. The present work provides a good example for understanding the interaction between Cu and nickel oxides, and helps to develop highly efficient non-noble metal catalysts for selective hydrogenation of aromatic nitro compounds to corresponding anilines.

In situ-formed cobalt nanoparticles embedded within carbonaceous matrix as highly efficient and selective catalysts for the hydrogenation of nitroarenes

Inhibiting the side reactions meanwhile promoting the hydrogenation of aromatic nitro compounds are the target for the production of functional amines. In this work, an easy-to-prepare heterogeneous catalyst with multilayered graphitic shells was successfully synthesized and applied. First of all, the structural features of catalyst reveal two possible catalytic mechanisms; in simple terms, 1) the metallic nanoparticles are covered with thin carbon layers with small cracks, where H2 can be diffused through and activated for the hydrogenation, and 2) the outer graphitic shell can be activated by the electronic interaction between inner metallic nanoparticles and outer graphene layer. Subsequently, the catalytic properties were tested in the hydrogenation of nitroarenes by a series of reaction conditions, hydrogen sources and substrates, and most of the nitro aromatics with functional groups were well tolerated in an excellent yield even under very mild industrially viable and scalable conditions. More surprisingly, this catalyst preformed highly selective hydrogenation on –NO2 and can further catalyze N-methylation for various tertiary amines by tandem reaction; not only that, a slight loss of catalytic activity was observed after recycling up to eight times, suggesting a potential routs to produce functional amines in scale-up application.

Nickel nanoparticles embedded in porous carbon-coated honeycomb ceramics: A potential monolithic catalyst for continuous hydrogenation reaction

The preparation method of porous carbon coated honeycomb ceramic monolithic catalysts is limited to traditional ideas. The porous carbon and the active metal particles are formed step by step. We have designed a novel preparation method and constructed a series of nickel-embedded porous carbon-coated (Ni@C) monolithic catalysts with different carbonization temperatures. Through the synchronous formation of porous carbon and active metal particles, the relationship between porous carbon and metal is changed from “supported” to “embedded”. The “embedded” structure between nickel particles and porous carbon formed at suitable carbonization temperature is an inseparable whole. Correlation characterization results show that the “embedded” structure has not changed the physical-chemical properties of porous carbon. However, the effect on the physical-chemical properties of nickel particles is very significant. Compared with conventional supported nickel-based monolithic catalysts (NiO/C), embedded nickel particles in the Ni@C monolithic catalyst have four characteristics. They are more uniform particle dispersion, smaller average particle size, more difficult to migrate and stable in metallic Ni0 form in air. Based on these advantages, Ni@C monolithic catalysts show better catalytic activity, stability and convenience in the continuous catalytic hydrogenation of aromatic nitro compounds.

Selective Hydrogenation of Aromatic Nitro Compounds Using Unsupported Nickel Catalysts

AbstractHydrogenation of nitroarenes has attracted renewed attention since it was discovered that non‐noble metal catalysts could selectively reduce nitroarenes with sensitive reducible groups. Here, we report the results of the chemoselective catalytic hydrogenation of nitroarenes with unsupported Ni NPs. Initial catalytic assessments showed high activity and selectivity, reaching conversions up to 99 % and 100 % selectivity towards the substituted anilines containing reducible groups such as halogens and nitrile. The recyclability test showed impressive stability of the catalyst up to the fifth run for the target product. Preliminary studies on the catalytic mechanism of the Ni NPs indicate that the nitrosobenzene might not participate as an intermediate in this reaction. Instead, a hydroxylamino adsorbed on the Ni surface is proposed. This work displays an accessible approach for synthesizing an active and selective catalyst for reducing nitroarenes in the presence of facile reducible substituents.

Comparison of Catalysts with MIRA21 Model in Heterogeneous Catalytic Hydrogenation of Aromatic Nitro Compounds

The vast majority of research and development activities begins with a detailed literature search to explore the current state-of-the-art. However, this search becomes increasingly difficult as we go into the information revolution of 21st century. The aim of the work is to establish a functional and practical mathematical model of catalyst characterization and exact comparison of catalysts. This work outlines the operation of the MIskolc RAnking 21 (MIRA21) model through the reaction of nitrobenzene catalytic hydrogenation to aniline. A total of 154 catalysts from 45 research articles were selected, studied, characterized, ranked, and classified based on four classes of descriptors: catalyst performance, reaction conditions, catalyst conditions, and sustainability parameters. MIRA21 is able to increase the comparability of different types of catalysts and support catalyst development. According to the model, 8% of catalysts received D1 (top 10%) classification. This ranking model is able to show the most effective catalyst systems that are suitable for the production of aniline.

Hydrophilic nickel phosphate nanoparticles: An efficient catalyst for the hydrogenation of nitroarenes

A clean and highly efficient chemical method was developed for the synthesis of hydrophilic nickel phosphate nanoparticles and the formation of nanoparticles was confirmed by discrete spectral techniques. The synthesized nanoparticles were found to be an efficient catalyst for transfer hydrogenation of aromatic nitro compounds. The reaction was carried out at room temperature using sodium borohydride as the hydrogen donor and the reaction was successful with remarkable yields.

Rhodium-terpyridine Catalyzed Transfer Hydrogenation of Aromatic Nitro Compounds in Water.

A rhodium terpyridine complex catalyzed transfer hydrogenation of nitroarenes to anilines with i-PrOH as hydrogen source and water as solvent has been developed. The catalytic system can work at a substrate/catalyst (S/C) ratio of 2000, with a turnover frequency (TOF) up to 3360 h-1 , which represents one of the most active catalytic transfer hydrogenation systems for nitroarene reduction. The catalytic system is operationally simple and the protocol could be scaled up to 20 gram scale. The water-soluble catalyst bearing a carboxyl group could be recycled 15 times without significant loss of activity.

Chemoselective hydrogenation of aromatic nitro compounds in the presence of homogeneous Pd based catalysts

The chemoselective reduction of aromatic nitro compounds to amine derivatives was easily performed with remarkable yields under ultrasonic conditions in a H2O/MeOH mixture (v/v = 1/4). In this process, commercially available BINAP.PdCl2 and NaBH4 were used as homogenous catalysts and the hydrogen source, respectively. The developed method has a high economic value and can be adapted to the industry. A variety of nitroarene derivatives were reacted by undergoing the BINAP.PdCl2 catalyzed reduction reaction. All nitroarenes were selectively hydrogenated to aromatic primary amines with quantitative yields in 15 min. The obtained primary amines were determined by 1H and 13C nuclear magnetic resonance spectroscopy.

Ru x Pd y Alloy Nanoparticles Uniformly Anchored on Reduced Graphene Oxide Nanosheets (Ru x Pd y @rGO): A Recyclable Catalyst.

In this work, RuxPdy alloy nanoparticles were uniformly decorated on a two-dimensional reduced graphene oxide (rGO) sheet by an in situ chemical co-reduction process. The resulting products were characterized by various physiochemical techniques such as X-ray diffraction, Raman spectroscopy, energy-dispersive X-ray spectroscopy, inductively coupled plasma atomic absorption spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. Further, the synthesized RuxPdy@rGO nanocomposites have been employed as a heterogeneous catalyst for three different catalytic reactions: (1) dehydrogenation of aqueous ammonia borane (AB); (2) hydrogenation of aromatic nitro compounds using ammonia borane as the hydrogen source, and (3) for the synthesis of aromatic azo derivatives. The present work illustrates the sustainable anchoring of metal nanoparticles over the surface of rGO nanosheets, which could be used for multifarious catalytic reactions.

Pd/C-catalyzed transfer hydrogenation of aromatic nitro compounds using methanol as a hydrogen source

We describe the selective transfer hydrogenation of aromatic nitro compounds to anilines using Pd/C as a heterogeneous catalyst with methanol as a green reductant. Nitroarenes bearing both electron-releasing and electron-deficient groups are amenable to this method and enable the synthesis of corresponding arylamines in moderate to good selectivities including the synthesis of butamben, a local anesthictic drug molecule. This new concise protocol is simple, ligand-free and does not require the supply of external molecular hydrogen.

Novel mesoporous Ag@SiO2 nanospheres as a heterogeneous catalyst with superior catalytic performance for hydrogenation of aromatic nitro compounds.

Mesoporous core–shell structure Ag@SiO2 nanospheres are constructed to prevent Ag nanoparticles from aggregation during the hydrogenation reaction. The prepared catalyst shows superior catalytic performance for hydrogenation of nitro compounds with 100% conversion and selectivity without any by-products, which also indicates good recycling performance for several times use.

A direct Z-scheme mechanism for selective hydrogenation of aromatic nitro compounds over a hybrid photocatalyst composed of ZnIn2S4 and WO3 nanorods

A direct Z-scheme mechanism photocatalyst constructed from ZnIn2S4 and WO3 is a versatile photoredox platform for selective hydrogenation and environmental remediation.

Autocombustion‐Promoted Synthesis of Lanthanum Iron Oxide: Application as Heterogeneous Catalyst for Synthesis of Piperidines, Substituted Amines and Light‐Assisted Degradations

AbstractAn autocombustion technique was adopted to synthesize the Perovskite structured Lanthanum iron oxide nanoparticles (LaFeO3, abbreviated as LFO NPs). This technique offered lots of benefits such as short reaction time along with quick heating rate. LFO NPs were fabricated at different calcination temperatures (300‐800 °C) through the aid of sucrose as chelating agent. The prepared LFO NPs were well characterized by various techniques like X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), Vibrating sample magnetometer (VSM), Ultraviolet‐Visible spectroscopy (UV‐Vis), Brunauer–Emmett–Teller (BET), X‐ray Photo‐Electron Spectroscopy (XPS) and Transmission electron microscopy (TEM) which affirmed that highly crystalline LFO NPs were obtained at 700 °C. Subsequently, the catalytic activity of the LFO NPs was surveyed for three independent approaches: (i) for the synthesis of functionalized piperidines through activation of carbonyl groups in the reacting partners (ii) for the sunlight‐assisted mineralization of health hazardous food colorant, Allura Red AC (iii) for the hydrogenation of nitro aromatic compounds (NACs) using NaBH4 (sodium borohydride) as source of hydrogen in aqueous medium at room temperature.